1. Field
The present invention relates to the field of display systems, and more particularly to devices which can position a cursor over selected locations on a computer controlled display.
2. Art Background
In many computer controlled display systems, it is desirable to allow the user to control the position of a cursor or the like by means which are external from the main computer keyboard. For example, a user may be required to repetitively choose software options displayed on a cathode ray tube (CRT), or may desire to input data in a diagram format into the computer system. In such situations traditional keyboard input systems are not as effective as a cursor control device commonly referred to as a "mouse".
In a typical "mouse" system, a hand-held transducer provides positional movement signals to the display system. Traditionally, the movement of wheels within the cursor control device are coupled to potentiometers to provide signals indicative of an X-Y position on the display screen (see U.S. Pat. Nos. 3,541,541; 3,269,190; and 3,835,464). Other mouse systems utilize rotating balls on wheels which are in turn coupled to rotate apertures interrupting beams of light, thereby providing positional signals to the display system (see U.S. Pat. Nos. 3,892,963 and 3,541,521).
One common disadvantage of cursor control devices found in the prior art is their cost. Typically, prior art cursor controls include costly mechanical parts which require precise alignment for proper operation. Moreover, it is not uncommon for these devices to exhibit a loss in accuracy over time as the mechanism wears. As computer display capabilities have become more advanced in terms of user real-time graphic interation, cursor control devices have become a necessity in many computer systems. Accordingly, there exists a need to provide a cost effective, simple and highly reliable cursor control device for providing signals indicative of X-Y positions on a computer display system.
As will be disclosed below, the present invention provides an improved cursor control device which overcomes the disadvantages of the prior art by utilizing a unitary frame structure for accurate alignment of all elements and simple assembly, as well as photo-optics to provide the required positional signals. In addition, a display system and method is disclosed for use in association with the cursor control device which permits a user to select command options simply by movement of the cursor over a "pull-down" menu bar.